The present invention relates in general to positioning and coupling apparatus, and in particular to a new and useful positioner which is capable of positively positioning one element with respect to another at a multiplicity of orientations. The invention is used in particular for positioning a sun visor extension but may be used in a wide variety of other applications.
Existing sun visors employed in land, sea and air vehicles are unable to prevent blinding glare when the sun is ahead and low on the horizon, which occurs during hours when the sun is rising and setting. Forward sun glare causes partial and sometimes complete loss of forward vision which causes fear and discomfort, and can place a vehicle and its occupants in danger of collisions with other vehicles or immovable roadside objects, with resulting injuries and fatalties as well as property damage.
Existing sun visors fail to overcome sun glare because they cannot be made big enough to do so without at the same time blocking a driver's vision of everything else ahead. Attempts to overcome the problem in the form of visor-wide dark filter flip-down attachments have proven unsatisfactory and have failed to achieve even a fingerhold in the marketplace.
However, an opaque auxiliary shield or paddle attachment will work, and would be useful if it could be manipulated and positioned easily and quickly with a minimum of attention. This is particularly important in the environment of a moving vehicle. An optimally effective embodiment of this concept calls for coefficients of friction between the various cooperating system members to be as low as possible, but at the same time consistent with the strict requirement that once the paddle or other suspended object is moved to a desired spatical position it will remain there despite any external forces. One such source is constant--i.e. gravity. Others are intermittent, such as vehicle vibrations, and in particular vertical shaking and jolting caused by unevenness, bumps, depressions and holes in the roadway.
When the movement of a system member is confined to the horizontal plane, a relatively low level of friction can provide positional stability. But where a member's movement is vertical or has a vertical component (vector) or where it can rotate in a vertical plane and is asymmetrically loaded, it is subject to gravity and inertial momentum and therefore requires a higher level of friction to maintain the required positional stability.
If, as in the case of the present invention, a cooperating member functions in both the horizontal and vertical planes, it would be advantageous to find means whereby the friction obtained during the horizontal movement will be less than that obtained during the vertical or rotational movement. Such means have been devised and comprise a key part of the present invention, as will be described in the following.